A shock absorber is mounted on a vehicle or the like for the purpose of damping vibrations generated in a vehicle body or a vehicle steering, for example.
In particular, when shock absorbers are used for the purpose of damping vibrations generated in a steering of a two-wheel vehicle, the shock absorbers desirably generate an equal damping force at each of the right and left sides against the swing of the steering in the lateral direction with respect to the neutral position of the shock absorbers.
JP2004-231036A published by Japanese Patent Office in 2004 discloses a shock absorber which has a circuit designed to use a single damping valve and allow hydraulic fluid filling the shock absorber to always pass through the damping valve in a one-way direction when flowing in and out of two pressure chambers in the shock absorbers.
More specifically, the circuit includes two flow paths providing fluid communication between one pressure chamber and the other pressure chamber, a passage providing fluid communication between the flow paths, and the damping valve provided at the midpoint in the passage. Further, in order for the hydraulic fluid to flow through the damping valve in a one-way direction, two check valves are provided in each flow path, that is, four check valves are provided in the entire circuit.